Heating with Fire Wood
Although heating your home with firewood can save money, there are several other factors to consider. Even the most efficient currently available wood heating appliances are still more polluting than modern heating oil and natural gas appliances. Burning wood produces smoke, and excessive smoke can cause health and other problems for your family and your neighbors. For example, recent increases in the number of inefficient outdoor wood boilers (OWBs) have sparked controversy about excessive smoke affecting peoples' enjoyment of their property and quality of life. Find out more about What to Do if You are Affected by a Neighbor's Outdoor Wood Boiler Smoke.
Some types of wood-fired heating units burn more cleanly and more efficiently than others. More efficient units provide more usable heat (sometimes referred to as BTUs or British Thermal Units, a standard used to measure heat) per unit of wood burned. The best high efficiency appliances may cost more initially, but they use less wood and create less smoke. The quality of the firewood also affects smoke levels and heating efficiency. Smoke is unburned fuel and is both unwanted air pollution and wasted fuel. Try to burn with as little smoke as possible. When planning to use firewood for heating, consider:
- the availability, effort and cost of getting dry (seasoned) firewood,
- the heating appliance options available for a particular home and their costs,
- the time factor in tending a wood fired-appliance,
- the increased costs of chimney cleaning and options for disposing of wood ashes, and
- the effect smoke may have on you and your neighbors.
Available Heating Technologies
If you are planning to heat with wood, the best advice is to choose the right appliance for your home. It is important to size the unit properly. Heating appliances are rated for the amount of heat they are able to produce over a period of time (typically reported in BTUs per hour). A correctly sized heating appliance is matched to the needs of the space to be heated and will run more efficiently. A heating contractor can help determine your home's heating needs. Oversizing a unit can result in inefficient operation and excessive smoke.
Three different types of wood-fired heaters are available for homes:
Wood Fired Hydronic Heaters
These devices heat water for whole house heating (and sometimes domestic hot water use). Two distinct designs are available outdoor wood boilers (OWBs) and dual-stage wood gasification boilers. OWBs can cause problems with excessive smoke and have been the focus of numerous community complaints, resulting in local and state regulations across the northeastern United States. Get more information on the pros and cons of hydronic heaters.
Wood Stoves, including Fireplace Inserts
These are usually best suited for heating a single room. Only install wood stoves certified by the US Environmental Protection Agency (EPA) since these burn cleaner than older models and are more efficient. These can still emit considerable amounts of smoke, but the smoke levels can be reduced by burning only well-seasoned firewood with dampers properly adjusted. EPA provides more information on wood stoves.
A fire in a fireplace can be very pleasant to enjoy, but fireplaces are perhaps the most inefficient means for providing heat to a home. If you want to use a fireplace for heating, consider installing an EPA-certified fireplace insert.
Wood Smoke and Health
Wood smoke can cause health problems. Wood smoke and the chemicals it contains are highly toxic. Wood smoke contains huge amounts of fine particles that are drawn deep into lung tissue when inhaled. Excessive wood smoke exposure can cause adverse health effects. Children, older people and individuals with cardiovascular or respiratory conditions are more susceptible to the effects of wood smoke.
To get the most out of firewood as fuel, it is important to properly dry (season) the wood. Well-seasoned firewood will start easily and burn bright with little smoke. Poorly-seasoned firewood will be difficult to keep burning, sap and water will hiss out of the ends of burning logs and the fire will produce much more smoke when it does stay lit. Smokey fires waste fuel. To season wood well, wood should be:
- Cut to proper length for use depending on the size of the appliance combustion chamber.
- Split to adequate sizes. For most uses, six-inches wide or less is a good size to allow for adequate seasoning and for optimal burning. Larger pieces are recommended for outdoor wood boilers, but large pieces require a longer time to season adequately.
- Stacked in a single row, up off the ground, in a sunny location open to breezes, covered on top but not on the sides (wood does not season as well when stacks are more than two rows wide).
- Allowed to dry over a full season, preferably two years for some of the more difficult to dry species such as red oak.
- Not stored too close to your house as firewood piles can attract termites or carpenter ants and provide a home for mice. Keep firewood dry at all times and periodically clean where wood is stored.
Cornell Cooperative Extension provides up to date information on wood burning technology.